4:28 PM - 4:43 PM
[SGL34-04] Estimated activities of submarine mud volcanoes off Tanegashima based on vertical profiles of pore water chemistry
Keywords:Submarine mud volcano, Porewater chemistry, nannofossils
We tried the quantitative evaluation of the difference in the vertical profiles of Cl– concentrations between MV#1 and MV#14 by using the one-dimensional unsteady advective diffusion model. As the initial state of the Cl– profile just after the mud eruption, we assumed that the Cl– concentration in the core bottom at MV#1 represents the original value of the deep sourced fluid, and the Cl– concentrations were constant from deep to surface immediately after the eruption. We estimated the advection rates of fluids and times after the mud eruption by fitting the numerically simulated depth profiles of Cl– concentrations to the observed depth profiles. As the result, advection rate and the time after the eruption at MV#1 were calculated to be 10–15 mm/y and 100–200 years, respectively, and those at MV#14 were estimated to be <0.1 mm/y and 8,000–10,000 years, respectively. The preliminary result of the nannofossils observation shows that the Quaternary and the Tertiary species mixed in the sediment sample obtained from MV#14 in which the Quaternary species are dominant in top 50 cm. The nannofossils records suggest that the hemi-pelagic Quaternary sediments have covered on the deep sourced Tertiary sediments which were conveyed to the sea surface from deep sedimentary realm by the mud eruption. The result is consistent with our estimation for the activity of MV#14 based on the Cl– profile.